Despite low immunization rates, infections with human papillomavirus (HPV) strains that are associated with cervical cancer have declined markedly among adolescent girls since 2006, when HPV vaccination was introduced.

Investigators led by Lauri Markowitz, MD, of the Centers for Disease Control and Prevention (CDC), analyzed HPV prevalence data from 2003 to 2006, before vaccination began, and afterward, from 2007 to 2010. They based prevalence determinations on 4150 cervicovaginal swab samples collected from girls and women aged 14 to 59 years during the earlier time period and 4253 samples taken after HPV vaccination was introduced.